Note: Descriptions are shown in the official language in which they were submitted.
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APPARATI1S AND METII017 FOR
TMPLANTATTON OF SENSORS
BACKGROUND OF THE INVENTTON
Field of the Tnvention:
The present invention relates to an apparatus arad method
for implantation of an itt uiuo sensor, and particularly to a
minimally invasive method for implanting a sensor.
Description of tine Prior Art:
Certain sensors, such as glucose sensors, are intended
l0 for use in uiuo, requiring that the sensors be implanted in a
fashion consistent with their use. However, it is also
desirable that the method of implantation ue guiclt, easy and
convenient. ~'he method of implantation is advantageously one
which is readily performed both by medical personzael
administering to a patient, and also by the person being
monitored. Since this person likely will not have medical
training, the method should be one which can be performed
reliably, such that the readings from the sensor are accurate.
The present invention provides a method which is readily
performed for the implantatiozi of a glucose or other sensor,
and which uses an apparatus which provides quick and reliable
results. While devices have existed for introducing a
catheter into small vessels subcutaneously, the introduction
of ittuiuo sensors in this manner has not been suggested.
In United States Patent No. 4,417,886, issued to
Frankhouser et al. on November 29, 1983, there is disclosed a
catheter introduction set. The Frankhouser patent describes
an assembly including a catheter mounted on an introducer
needle, with floe tip of the needle extending slightly beyond
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the end of the catheter. A wire guide is received within the
needle and attached to a guide tube extending rearwardly from
the needle. In use, the needle is insertec'1 into the lumen of
the vessel, the spring wire guide is advanced into the
vessel, and the catheter is them advanced forwardly to track
the spring wire guide into the vessel to tle desired
position. Thereafter, the spring wire guide and needle are
removed.
A comparable device, but without the wire guide, is
currently marketed by MiniMed Technologies of Sylmar,
California under the name SOF-SET. Tiuis device includes a 24
gauge needle received within a short 24 gauge catheter. The
needle includes a handle, and is used to introduce the
catheter into tine body by-piercing through the skin. Tlie
catheter extends from a support adapted to be secured to the
sltin. A length of tubing also extends from the support, and
communicates with i:he catheter upon withdrawal of the needle.
Methods and assemblies for the introduction of duel lumen
catheters have also been identified. Dual lumen catheters
have been noted as providing two means for access to a
vessel, such as for withdrawal of blood samples and the
infusion of drugs. An introducing needle assembly similar to
that described in the Frankhouser patent, but including a
double lumen needle, is disclosed in United States Patent
No. 4,935r008, issued to Lewis on dune 19, 1990. Similarly,
the TWTN CATHC9~ groduct from Arrow International, Inc.,
comprises an introducer including a two lumen catPreter. One
lumen of tire catheter is round and receives a needle therein,
and the other lumen has a C-shaped cross section and
surrounds a portion of the round lumen.
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SUMMARY OF INVENTION
A broad aspect of the invention provides an
apparatus for implantation of a sensor beneath the skin
surface which comprises: a housing; a dual-lumen tube having
a proximal end attached to said housing and having a distal
end projecting from said housing, said tube, including the
distal end, defining a first lumen and a second lumen; a
needle received within the first lumen of said tube, said
needle including a proximal end and a pointed distal end
extending outwardly of the distal end of said tube; and a
sensor received within the second lumen of said tube, said
sensor including a sensing element positioned within the
second lumen adjacent the distal end of said tube and
outside of said housing, said sensor further including means
for communicating information sensed by the sensing element
to a location spaced from the sensing element, whereby
implantation of said sensor is accomplished by forcing said
needle and said tube into a desired location beneath the
skin surface.
Another broad aspect of the invention provides a
method for implantation of a sensor beneath the skin surface
which comprises the steps of: a) providing an implanting
device which includes a housing, a dual-lumen tube having a
proximal end attached to the housing and having a distal end
projecting from the housing, the tube, including the distal
end, defining a first lumen and a second lumen, a needle
received within the first lumen of the tube, the needle
including a proximal end and a pointed distal end extending
outwardly of the distal end of the tube, and a sensor
received within the second lumen of the tube, the sensor
including a sensing element positioned within the second
lumen adjacent the distal end of the tube and outside of the
housing, the sensor further including means for
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communicating information sensed by the sensing element to a
location spaced from the sensing element; and, b) pressing
the needle through the skin surface to position the distal
end of the tube to a desired location beneath the skin
surf ace .
Briefly describing one aspect of the present
invention, there is provided an apparatus for implantation
of a sensor which comprises a housing, a dual-lumen tube
attached to the housing, a sensor received within a first
lumen of the tube, and a needle received within a second
lumen of the tube. The tube and needle are sized such that
the needle is inserted under the skin to the level of the
housing, providing a desired placement of the sensor. The
needle is then.removed and the remainder of the apparatus is
secured against the skin during the time that monitoring
with the sensor is desired. A related method for implanting
an in vivo sensor is also provided.
It is an aspect of the present invention to
provide a simple, quick and reliable apparatus and method
for implantation of an in vivo sensor. A further aspect of
the present invention is to provide an apparatus and method
which reliably places an in vivo sensor in a desired
position beneath the user's akin. Further aspect and
advantages of the present invention will be apparent from
the drawings and description of the preferred embodiment
which follows.
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HRIEF vESCRIPTIUIJ OF TIIE DRAV~IINGS
FIG. 1 is a side, partially cross=sectional view of an
apparatus for the subcutaneous implantation of an in viuo
sensor constructed in accordance with the present invention.
FIG. 2 is a cross-sectional view of the dual-lumen tube
useful in the present invention, taken along the lire 2-2 in
FIG. 1 and looking in the direction of the arrows.
FIG. 3 is a cross-sectional view of the dual-lumen tube
useful in the present invention, taken along the line 3-3 in
FTG. 1 and looking in the direction of the arrows.
FTG. 4 is a side, partially cross-sectional view of the
apparatus of FIG. Z upon use for implantation of a sensor
subcutaneously, and particularly showing the apparatus with
the needle removed and the cover in the closed position.
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DESCRIPTION OF THE PREFERRED EMBODTMENT
For the purposes of promoting an understanding of the
principles of the invention, reference will now be made to
the embodiment illustrated in the drawings and specific
language will be used to describe the same. Tt will
nevertheless Ice understood that no limitation of the scope of
the invention is thereby intended, such alterations and
further modifications in the illustrated device, and such
furtYrer applications of the principles of the invention as
illustrated therein being contemplated as would normally
occur to one skilled in the art to which the invention
relates.
The present invention provides an efficient and easy to
use apparatus and method for implanting itt t~ivo sensors. 'flye
apparatus is simple in construction and rnay be readily used
by medical personnel or by the user of the sensor. This
apparatus and method have wide spread application for use
with sensors adapted for implantation in this manner. By way
of example, the invention is described with respect to use
with glucose sensors. but the invention is not limited to use
with these types of sensors.
Referring in particular to the drawings, there is shown
an apparatus 10 for subcutaneous implantation of a sensor.
The apparatus includes a housing 11 and a dual lumen tube 12
attached thereto and extending outwardly of the bottom
surface thereof. A needle 13 is received within one of the
lumen of the tube 12, and a sensor 14 is received within the
other lumen. The needle is used to introduce the tube
subcutaneously, and is thereafter removed, leaving the tube
and the sensor 14 retained beneath the skin for use.
The housing 11 provides several functions with respect to
the overall implantation apparatus. The housing comprises a
lightweight structure which supports the tube 12 and contains
the needle 13 prior to use. In a preferred form, the housing
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includes a cover 15 which provides access to the proximal end
of tube 12, and therefore to the needle 13. :Tire needle
includes a handle 16 to facilitate its removal from the tube
12 after irnplantati.on has been accomplished. The housing 11
defines a cavity within which the handle is received, anrl
which is accessed by opening the cover 15. The cover also
closes the cavity and therefore the proximal end of the tube
12 after the needle has been removed and while the sensor is
in use.
Attached to the housing at its proximal end is the
dual-lumen tube 12. This tube defines a first lumen 17 and a
crescent-shaped, second lumen 18. The first lumen is
preferably round and receives the needle 13 therein. Tkre
sensor 14 is received within the second lumen 18.
Preferably, the tube 12 includes an opening 19 at the distal
end. 7.'he sensor 14 includes a sensing elernent 2U which is
positioned within the opening 19 to be exposed exteriorly of
the tube.
The needle l3 is used for inserting the tube 12 and
associated sensor 14 beneath the surface of the skin. The
needle has a pointed distal tip 21 for piercing the skin.
The tube 12 includes a distal end 22 having an external
surface which tapers inwardly in the distal direction, thus
presenting a low profile for insertion through the skim. Tk~e
tapera.ng of the distal end of the tube is conveniently
accomplished by "pulling down" the tube over the needle. The
pointed tip of the needle extends a slight distance outwardly
of the distal~end of the tube.
In practice, the apparatus 10 is grasped by its housing
11 and the needle is forced through the skin. The closely
conforming tube 12 is carried through the skin by the
introducing needle and the distal end of the tube is thereby
positioned beneath the skin surface. After placement of the
tube, the cover 15 is opened and the needle is removed frorn
the tube by use of handle ls. The cover is then closed (T'IG.
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9). The bottom surtace of the housing is preferably provided
with an adhesive layer 23 to attach the housing to the skin
upon implantation of the sensor.
The sensor 14 may be any of a variety of sensors which is
intended for in. vivo wse and which is adapted for '.
implantation by use of the apparatus and method described.
For example, the sensor may be a glucose sensor such as.
described in R.J. Morff, D. Lirson, K.W. Johnson, J.J.
Mastrototaro, C.C. Andrew, A.R. Fotvin, "Reproducible .
Microfabrication of Electroenzymatic Glucose~Sensors on a
Flexible Substrate," P~yc~. 1st WcL Ir a Congress on Hios~~sors,
(May 2-4, 1990); and J.J. Mastrototaro, K.W. Johnson, R.J.
Morff, D. Lipson, C.C. Andrew, "An Electroenzymatic Glucose
Sensor Fabricated on a Flexible Su.bstrate." Proc. Third
international Meetinyo~, Che~aical Sen~rs, (Sept: 24-26,
1990). The glucose sensors described therein are sized and
configured to be conveniently received within the second
lumen 18.
Means are provided for communicating information from the
sensing element to a location spaced from the sensing
element. The sensor preferably includes a flexible substrate.
upon which are mounted the sensing elements and wires
communicating therewith. In this embodiment, the sensing
element 20 is preferably positioned within the opening 19,
and the substrate 24 and supported wires 25 together extend
from the sensing element through the second lumen 18. The
wires and substrate exit the tube adjacent its proximal end.
A filler 26 may be used to assist in securing the tube to the
housing, and also to contain the wires 25 exiting from the
proximal end of the tube. These wires are connected with
means for receiving information from the sensing element;
which means may be located conveniently within-the housing.
11.' Alternatively, the wire leads may be connected to an
external device, in which case a connector (not shown) may be
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incJ.uded. Such means, whether interna:L or external, may
further be provided for displaying and/or recording tl~e
sensed information.
The apparatus is simple and readily produced. The
components may be formed from a variety of known materials
suitable for medical applications, particularly biocompatible
materials useful for production of the needle, dual-lumen
tube and the like which are inserted under the skin. Typical
materials for the tube 12 include polyethylene,
polytetrafluoroethylene, polyurethane and silicone, the last
one providng greater flexibility: Sizing of the apparatus is
determined by the nature of the sensors to be used and tkre
required placement of the sensors subcutaneously. In a
typical example, the tube 12 comprises 19 gauge tubing, and a ,
21 t;o 27 gaugb syringe needle is usod in the circular central ,
lumen.
'.Che apparatus and method of flue present invention provide
fox the quick, simple and accurate placement of an in uiuo
sensor. The system is easily used without the need for
medical personnel. Consequently, the implantation can be
performed conveniently at home or elsewhere. The needle
provides rigidity during implantation, but upon removal the
tube has flexibility desirable, to reduce local irritation and
to increase user comfort.
The apparatus may be provided in sterile packaging, arid
the user simply removes the apparatus and performs the
implantation as described. The apparatus either includes flue
necessary recording/displaying means, or a connector is
provided for coupling the wire leads to a suitable, external
monitoring device.
While the invention has been described in detail in the
foregoing description, the same is to be considered as
illustrative and not restrictive in character, it being
understood that only the preferred embodiment has been
described and that all changes and modifications that come
within the spirit oL tkre invention are desired to be
protected.
